Many produce products are harvested and packed in the field into containers, which are currently shipped in bulk to stores where they are unpackaged and sold to consumers. Many of these produce items require substantial post-harvest cooling in order to enable shipping over long distances and to prolong shelf life. Many such produce products are advantageously subjected to hydrocooling to effect rapid efficient cooling before they are shipped out in refrigerated or insulated shipping containers. Among the many produce products that benefit from such processing include, but are not limited to, asparagus, beans, peas, asparagus, zucchini, cucumbers, radishes, carrots, celery, beets, sweet corn, apples, cantaloupes, peaches, and various greens and other produce products. A wide listing of such products can be found for, example, in Extension Service publication AG-414-1, Introduction to Postharvest Cooling and Handling Methods, which also addresses many of the concerns associated with hydrocooling.
Most fresh fruits and vegetables require thorough cooling immediately after harvest in order to deliver the highest quality product to the consumer. Proper cooling delays the inevitable quality decline of produce and lengthens its shelf life. Most wholesale buyers now require that fresh produce items be properly and thoroughly cooled before they are shipped to market.
When warm produce is cooled directly by chilled water, the process is known as hydrocooling. Hydrocooling is an especially fast and effective way to cool produce. Modern technologies have made hydrocooling a convenient and attractive method of postharvest cooling on a large scale.
As stated previously, many types of produce respond well to hydrocooling. This is particularly true with respect to produce items having a large volume relative to their surface area that would otherwise be difficult to cool. Such products are now quickly and effectively hydrocooled. Additionally, unlike air cooling, no water is removed from the produce during cooling. In fact, slightly wilted produce may sometimes be revived by hydrocooling. Hydrocooling is fast and can easily accommodate large amounts of produce.
In general, a hydrocooler produces chilled water and then moves this water into contact with the produce. This can be accomplished using a number of methods. However, most commonly, chilled water is pumped into contact with the produce. The water warmed by the produce is commonly gathered and recirculated through a cooling element where it is again showered onto the produce. Vapor-compression refrigeration systems similar to an air conditioners or refrigerators are commonly used to cool the water. Alternatively, some hydrocoolers do not use a refrigeration system. Instead, crushed or chunk ice is used to cool the water. Typically, large blocks of ice are crushed and added as needed to a water reservoir attached to the hydrocooler. In either case the basic idea is the same, the produce is brought into contact with cooling water to effectuate rapid cooling of the produce.
The design of produce packaging and the stacking arrangement is critical to the heat transfer process in hydrocooling. A variety of known produce packages are now used in hydrocooling. These packages include wire-bound wooden crates, waxed fiberboard cartons, mesh poly bags, and bulk bins. Palletized packages can be hydrocooled if they are carefully stacked to allow water to enter the packages. Most if not all present hydrocooling containers are large containers constructed to facilitate maximum water flow. Heretofore, small consumer sized containers are not used because they generally exhibit poor water flow characteristics. This is critical because, if the water flows around and not through the containers, little contact is made with the produce and consequently little cooling occurs. Additionally, such packages must be robust enough to protect delicate produce contained within the package (e.g., asparagus, grapes, and the like). This is why mesh poly bags that are sometimes used have problems. So, in the present art, produce is commonly placed, in bulk, in large waxed cardboard cartons that are subjected to hydrocooling processes. Typically, large wire-bound cartons and crates large volumes of open space are used for hydrocooling because they allow for sufficient entry of water. For example, 20-bushel bulk bins are commonly used because the cool water can easily percolate down through the product facilitating effective cooling.
Although hydrocooling is an excellent cooling method, it does have certain limitations, for example, hydrocooling wets the produce. Such wet produce provides excellent sites for postharvest diseases. Additionally, produce is particularly susceptible to postharvest diseases when it is stressed by too much or too little water, high rates of nitrogen, or mechanical injury (scrapes, bruises, or abrasions). This last factor is particularly at issue in the present art because during unloading and unloading of the bulk produce (for example, when unloaded for display and sale in a store) significant damage can occur to the produce. Commonly, as much as 20% of a produce lot is lost through wastage in this way. Additionally, water pooling at the bottom of present art crates presents some problems. For example, because the hydrocooling water is recirculated, it can spread disease from a few infected items to all the produce hydrocooled thereafter. Commonly, disinfectants such as chlorine are added to the coolant to reduce the incidence of disease. However, this presents its own problems, as chlorine can damage the produce (for example, by surface bleaching, etc.) if it pools around the produce in too high a concentration. Thus, it is important that the water not pool around the produce in too high a quantity.
Additionally, as alluded to above, produce suffers extensively from customer/clerk handling in stores once set out for display. For example, in the case of asparagus, asparagus spears are cut in the field and rubber banded together in batches and then gathered in bulk in wax boxes for hydrocooling. Once cooled the asparagus is maintained in a refrigerated shipping compartment in the boxes (which do not circulate air particularly well) until it is delivered to its desired destination (typically a retail outlet). The batches are then unloaded and arranged for display. Customers then repeatedly handle and examine the batches resulting in serious amounts of product having to be discarded due to damage. Additionally, with each handling there arises an added risk of transferring pathogens onto the produce. None of this is desirable and a solution to these shortcomings is desirable.
What is clearly needed is an improved hydrocooling and packaging system, which will enable small batches of produce to be individually packaged and protected. Additionally, the system should enable effective hydrocooling of large quantities of produce in large containers while also enabling effective high volume cooling water flow into each of the individual packages enabling effective hydrocooling of the produce contained therein. Additionally, the system should enable effective drainage of the cooling water out each of the individual produce packages as well as the large containers thereby preventing substantial pooling of water beyond what is necessary to prevent the produce from drying out. Moreover, it would be advantageous to provide a cooling system that facilitates efficient airflow through the individual packages of the system in order to maximize air transfer rates. Such systems can result in more effective cooling. To make such an improved system feasible, it must interface with commonly used and preferred materials handling apparatus, for example, the standard forty by forty eight inch pallets in current use in the grocery industry. Moreover, where a different pallet size has been adopted as standard, for instance in another country, what is further needed is a system which can be scaled to effect the advantages hereof in that pallet system.
The baskets of such a system should be capable of being formed in the preferred size or quantity configuration preferred by the end consumer, while simultaneously maximizing their footprint on existing pallet technology. The baskets should be formed to minimize bruising and other damage to the produce packed therein. Furthermore, such a system should provide for the mixing of lots of different types, quantities and sizes of produce on a single pallet without substantial losses of packaging efficiency occasioned by differing types of misaligned trays. Finally, it would be desirable if the system enabled the stacking of one or more layers of filled produce containers.
If possible, the system should be formed utilizing existing equipment and machinery from materials of the same or lesser cost than currently available produce packages.